Comment 2 for bug 1516083

Reviewed: https://review.openstack.org/245241
Committed: https://git.openstack.org/cgit/openstack/cinder/commit/?id=7cf6d6457c74a63ec7df282c402fcd31a60a12af
Submitter: Jenkins
Branch: master

commit 7cf6d6457c74a63ec7df282c402fcd31a60a12af
Author: zhangsong <email address hidden>
Date: Sat Nov 14 00:44:53 2015 +0800

    Fix the bug of can't get the desired image info

    When we use 'qemu-img info' command to get image info, some kinds
    of image may show an 'unavailable' disk size. For example:

    $qemu-img info sheepdog:volume-1af1afa0-7820-4063-9b90-4fa6161a74a9
    image: sheepdog:volume-1af1afa0-7820-4063-9b90-4fa6161a74a9
    file format: raw
    virtual size: 10G (10737418240 bytes)
    disk size: unavailable

    $qemu-img info -f rbd rbd:data/foo
    image: rbd:data/foo
    file format: rbd
    virtual size: 10G (10737418240 bytes)
    disk size: unavailable
    cluster_size: 4194304

    The current code didn't consider 'unavailable' size, and it will
    raise a ValueError in this case. This patch fixed this bug by
    adding the judgment of 'unavailable' size.

    Change-Id: Ic5f3b80e172baaafc07432319f8aa24bf117b392
    Closes-Bug: #1516083